[Gealii]

if your worried about the salt getting stuck on top of it you could build a belly pan that mud truck racers use, its fully connected in the front 1/4 of the truck then it breaks off remains smooth all the way back with gaps on the side and rear. It would allow you to wash the salt out with ease while keeping most the gains from a smooth underbelly.

The mud trucks use it to glide easily through the mud and then the mud is not stuck on top of the pan creating more weight it just falls out as more water/mud mix flushes through it